Use of physiology to evaluate procedural result after PCI CTO

It is known that a suboptimal stent result (SSR) can lead to future PCI's .This
is already the case for SSR after regular PCI's, however could be even more
evident for SSR after a CTO PCI.
SSR is not always visible on a normal coronary angiogram. However, early
detection of a SSR and accordingly direct optimization of the stent result can
lead to a better and more sustainable result. The aim of this study is to
investigate if performance of post-PCI coronary physiology measurements,
including RFR (resting full-cycle ratio), FFR (fractional flow reserve), IMR
(index of microcirculatory resistance) and coronary flow reserve (CFR) and the
addition of OCT (optical coherence tomography), will detect SSR and lead to a
better understanding of the functional and anatomical aspects of CTO PCI to
guide further optimization of procedural results. The pressure wires and OCT
camera that are used for the study-related measurements are commonly used
interventional tools.

Primary objective:
-To assess the predictive value of post-PCI RFR (resting full-cycle ratio) and
FFR (fractional flow reserve) with regard to SSR (suboptimal stent result) in
CTO (chronic total occlusion) patients.

Secondary objectives:
- To assess the predictive value with regard to SSR of the RFR and FFR gradient
across the stented segment
- To evaluate the correlation between positive RFR (<=0.89) and positive FFR
(<=0.80) with regard to SSR following angiographically satisfactory CTO PCI.
- To evaluate the correlation between post-PCI physiology (RFR, FFR, CFR, IMR)
and SSR with anginal complaints (measured using the Seattle Angina
Questionnaire [SAQ]), cardiovascular events and other clinical classifications
(CCS and NYHA)
- To assess the impact on physician-decision making based on OCT and physiology
findings.

Exploratory objective:
- To assess the change in RFR, FFR and other physiological parameters over time
(subset of patients)

Prospective, multicentre, non-randomised investigator-initiated trial with a
non-inferiority design.

After angiographically successful PCI of the CTO target vessel (no remaining
lesion proximal or in-stent >= 30%, confirmed in two orthogonal projections with
an angle >=25 degrees apart), physiologic measurements must be performed in this
vessel: Pd/Pa (pressure-distal / pressure-aorta = ratio of mean resting distal
coronary pressure to aortic pressure), RFR (resting full-cycle ratio), CFR
(coronary flow reserve), IMR (index of microcirculatory resistance), FFR
(fractional flow reserve). Additional OCT will be performed during the index
procedure to assess the anatomic stent result. OCT may also be performed during
a staged procedure within 4 ± 2 weeks when indicated (i.e. high contrast use,
procedural duration, major dissection or other safety reasons according to the
operator). For patients with a remaining intermediate stenosis
(angiographically 30-90%) in a non-CTO vessel or major side branch of the CTO
vessel with diameter >= 2mm, clinically indicated FFR guided PCI will be planned
within 4 ± 2 weeks. During this staged procedure, intra-coronary physiologic
assessment (RFR, FFR, CFR and IMR) will be repeated in the CTO vessel for
exploratory objectives (before additional PCI).

PCI and medical treatment will be performed according to the international
guidelines. The anticipated benefit is improvement of our knowledge on how to
optimize stent results in CTO PCI. Because the pressure wires and OCT camera
that are used for the study-related measurements are commonly used
interventional tools, this poses no study-related additional risk for
participating patients. Due to study-related measurements both procedures (as
part of standard care) will be moderately prolonged, most likely by
approximately 15 minutes. Patients will not be exposed to extra visits. Based
on the available data we consider the risks and burden of this research project
to be small. With minimal effort and risk, subjects included in this trial are
able to contribute to research to that may improve the treatment of CTOs, which
may have large impact on clinical practice and guidelines. This study will be
conducted in full compliance to the principles of the Declaration of Helsinki.